# celsius = float(input("请输入一个数字:"))
# fahrenheit = (9 / 5) * celsius + 32
# print(f'{fahrenheit}')
# print("""Hello World! This is "Python" """)
# print('Hello World! This is "Python" ')
# try:
#     num1 = int(input())
#     num2 = int(input())
# except:
#     print("error")

# print(num1 + num2)
# r = 5 
# a = 6 
# b = 1 
# c = 2
# d = 2 
# # 4 / 3 * (r + 34) - 9 * (a + b * c) + (3 + d * (2 + a)) / (a + b * d)
# print(4 / 3 * (r + 34) - 9 * (a + b * c) + (3 + d * (2 + a)) / (a + b * d))
# print(int("4.5"))
# i = int(True) #1
# j = int(False) #0
# b1 = bool(4)
# b2 = bool(0)
# print(i, j, b1, b2)
nof = float(input())
print(nof * 0.305)
